This invention relates to a safety arrangement for systems having parts spatially moved, in particular for manipulation devices, such as industrial roboters, and for self-driving transportation devices, including electric switch elements which cause a signal upon collision of the moved parts with persons or objects, said signal shutting down the moved parts or initiating an emergency operation program which causes for instance a sequence of motions opposite to the direction of collision.
Such safety arrangements are known and find general application in particular for securing automatic doors at elevators and public transportation vehicles. The electric switch elements are mostly deviced as resiliently supported strips or sensors or strips or sensors loaded with a predetermined force. The efficiency of such arrangements has as a requirement that the site of collision at which the moved parts may strike the persons or objects is known at least regarding a plane or a line.
A safety arrangement is also known from German Offenlegungsschrift No. 2,644,608, wherein, however, the site of collision at least regarding a line or plane must be such as is the case for instance for a roll gate. Therein, a signal generator arranged substantially along the entire leading edge of the roll gate is used. The signal generators are not suited to operate as area signal generators since a resistance variation in relationship to the overall resistance is detected in the non-compressed condition. In the case of large-volume constructions as required for instance for safeguarding industrial roboters unfavorable conditions result between the resistance variation relative to the overall resistance, so that either a high sensitivity of the system is required and thus no proper response is obtained or such a large volume must be deformed that for instance a touching of the safety arrangement with a finger causes no shut-down signal.